Refining connectivity rules
Update: Comments are now locked on this thread. If you have questions, please ask in them in the ArcGIS Utility Network Questions community.
When you use the Migration toolset to create your own utility network, the tool creates a generic network model that is configured to help you get started as quickly and easily as possible. One of the limitations of using the Migration toolset to create a utility network is that it doesn’t include any of the industry-specific configurations found with the utility network foundations that allow your data to behave more like a real-world system. These configurations enforce strict data quality requirements that will create topology errors when your data doesn’t conform to the configuration of your network model (connectivity rules, edge connectivity policy, etc).
You can expect to see more errors if you migrate your data to a Utility Network Foundation than if you use the migration toolset. These errors represent locations where the data needs improvement. So how do customers who use the Migration toolset configure their data to enforce stricter data quality requirements?
You can configure your data with industry specific behaviors. Some of these configurations, like adding terminals, will impose more constraints on how you edit your data. Other configurations, like creating subnetworks, will unlock new tools you can use for quality assurance and quality control.
One of the most meaningful changes you can make to your data model to improve data quality, and the editing experience, however, is to modify your connectivity rules.
What are connectivity rules?
Network rules in the utility network define what features are allowed to connect, attach, or contain other features. Connectivity rules are a subset of network rules which govern how network features can be connected through geometric coincidence or connectivity associations. These rules influence the editing experience through the snapping environment and ensure the utility network specific editing tools (Modify Terminal Connections, Modify Associations, etc) only present you with valid options.
When the Migrate To Utility Network tool runs it creates an initial set of rules that allow every type of junction/device feature to connect to every type of edge feature in the same domain. Each model produced by this tool is unique so the tool must allow everything to be connected.
This approach is quite different from what happens if you migrate your data into a foundation model. Each Utility Network Foundation contains a known set of asset groups and asset types and includes thousands of connectivity rules that determine what and how these features can be connected.
The Migration toolset contains several tools you can use to review and adjust the connectivity rules of any utility network. This process is particularly important for customers who use the Migrate To Utility Network tool to create their utility network as it allows them to quickly adjust their rules based on the connectivity in their GIS.
Modifying connectivity rules
The ArcGIS Utility Network has tools that enable you to remove rules from your model when you don’t want to allow certain features to connect. When new asset types are added to your model, tools also exist to add rules to your model that define how these new features are allowed to connect to the existing features in your model.
Given that most utility networks include hundreds or even thousands of connectivity rules, any process for reviewing them is going to take time. Making decisions about what things are allowed to connect requires a knowledge of the GIS model and drawing standards, but it also requires an operational understanding of the types of equipment being modeled and what configurations are possible in the real world.
Removing a connectivity rule indicates that the features can never be connected in the GIS. Before you remove a rule, you need to confirm there are no instances of that connectivity in your GIS as well as in the real world. Never underestimate the creativity of a field crew working to make repairs to a system during an emergency!
With this information in mind, there are two things to consider before we make changes to rules:
- What types of features are connected in the data?
- Which types of features should be allowed to be connected?
- Are any of the invalid connections outliers that need to be allowed?
Fortunately, the Migration toolset contains tools that can help you answer these questions.
Analyzing existing connectivity
Identifying what types of features are coincident to create a set of rules based on that analysis sounds like a relatively straightforward spatial analysis question. Depending on how technical you are, it could take anywhere from a few weeks to a few months to build the scripts and tools to achieve this goal, excluding time spent with subject matter experts deciding on a final set of connectivity rules. However, the Analyze Network Data tool in the Migration toolset can do all this work for you in just a few minutes.
Note: For this process to work correctly, you must analyze a utility network that doesn’t have any junction-edge and edge-junction-edge rules configured.
The Analyze Network Data tool analyzes your data for common topological errors that need to be corrected, including features that are spatially coincident and not allowed to connect. When you use a model built by the Migrate To Utility Network tool this isn’t a problem you will encounter because of the rules that are created between all junction and edge features. However, if you were to create a copy of your utility network without any junction-edge or edge-junction-edge connectivity rules for connected features, the tool will report a connectivity error for all the features that are spatially coincident.
Note: Do not make these rule changes directly in production. You should copy your data to a local file/mobile geodatabase and test your configuration there due to the iterative and disruptive nature of this analysis.
This report allows you to quickly identify what kinds of features are connected, how many of each type of connection exists, and where these are in your data. This information can then be reviewed with subject matter experts like engineers, field crews, and operators to make informed decisions about what should be allowed to be connected.
If you still have a question about whether something should be allowed to be connected, the final arbiter of that decision is always reality. Because the locations layer contains features for all the connectivity issues, this layer can be shared with field crews to verify any locations in the field you have questions about.
Creating Rules
Once you’ve identified what types of features you want to be connected, your next task is to add the supporting rules to your network. This ensures that only features with rules can be connected, as any features attempting to be connected without a corresponding rule will be reported as topology errors.
Manually adding all these rules would be a tedious task. Fortunately, the Analyze Network Data tool creates a CSV file of rules that can later be imported into a utility network. You should modify this CSV file as part of the error review process with your subject matter experts to only include rules for features you agree should be connected.
Once the CSV file has been modified to contain only the approved rules, you can apply it to your utility network using the Import Rules tool. After importing rules and enabling the network topology your data will be connected using the newly imported rules and topology errors will be generated for any features without a supporting rule that are not allowed to connect.
Conclusion
In this article you learned about the importance of connectivity rules to data quality, and how you can refine your connectivity rules using spatial analysis and the tools available in the Migration toolset. Reviewing and adjusting your rules is an effective way to document and understand your model while also improving your data quality. With these new rules you will only be able to ensure that connectivity only exists between features that have been approved to connect. If you attempt to connect any other types of features, the utility network will generate an invalid connectivity topology error.
Refining your connectivity rules is an optional part of configuring and deploying a utility network, but it’s a worthwhile time investment to perform with your data before you go live. Not only will this help you refine your connectivity rule and resolve any outliers, but it can often cut the number of rules in your model in half!
However, don’t think you need to follow this process every time you want to change the rules. If you are making minor adjustments to your connectivity rules to account for small schema or business process changes you should use the Add Rule and Delete Rule tools. Try the Configure rules for a utility network tutorial if you are interested in learning more about maintaining the rules of a utility network.
For more information about the migration toolset, including how to access them, read the Get Started with the Migration toolset article on the Esri Community Site! You can not only ask questions there, but you can download these tools and find additional resources covering topics like configuring your own model and data migration.
